531.
1) 2m + 3n = 2m + 3n = 2m(m-n)+3n(m+n) =
5m+5n 5m-5n 5(m+n) 5(m-n) 5(m+n)(m-n)
=2m²-2mn+3mn+3n² = 2m²+3n²+mn
5(m²-n²) 5m²-5n²
2) 7x - 2x = 7x - 2x = 7x(x-y)-2x(x+y) = 7x²-7xy-2x²-2xy =
3x+3y 3x-3y 3(x+y) 3(x-y) 3(x+y)(x-y) 3(x²-y²)
=5x²-9xy
3x²-3y²